FBI warns of ‘destructive’ malware after Sony attack

The FBI warned US businesses on Monday that hackers have used malicious software to launch a destructive cyber attack in the United States, following a devastating breach last week at Sony Pictures Entertainment.

Cybersecurity experts said the malicious software described in the alert appeared to describe the one that affected Sony, which would mark first major destructive cyber attack waged against a company on U.S. soil. Such attacks have been launched in Asia and the Middle East, but none have been reported in the United States. The FBI report did not say how many companies had been victims of destructive attacks.

“I believe the coordinated cyberattack with destructive payloads against a corporation in the U.S. represents a watershed event,” said Tom Kellermann, chief cybersecurity officer with security software maker Trend Micro Inc. “Geopolitics now serve as harbingers for destructive cyberattacks.”

The five-page, confidential “flash” FBI warning issued to businesses late on Monday provided some technical details about the malicious software used in the attack. It provided advice on how to respond to the malware and asked businesses to contact the FBI if they identified similar malware. The report said the malware overrides all data on hard drives of computers, including the master boot record, which prevents them from booting up.

“The overwriting of the data files will make it extremely difficult and costly, if not impossible, to recover the data using standard forensic methods,” the report said.

The document was sent to security staff at some U.S. companies in an email that asked them not to share the information.

The FBI released the document in the wake of last Monday’s unprecedented attack on Sony Pictures Entertainment, which brought corporate email down for a week and crippled other systems as the company prepares to release several highly anticipated films during the crucial holiday film season.

A Sony spokeswoman said the company had “restored a number of important services” and was “working closely with law enforcement officials to investigate the matter.” She declined to comment on the FBI warning.

The FBI said it is investigating the attack with help from the Department of Homeland Security. Sony has hired FireEye Inc’s Mandiant incident response team to help clean up after the attack, a move that experts say indicates the severity of the breach.

While the FBI report did not name the victim of the destructive attack in its bulletin, two cybersecurity experts who reviewed the document said it was clearly referring to the breach at the California-based unit of Sony Corp.